AVS 49th International Symposium
    Electrochemistry and Fluid-Solid Interfaces Tuesday Sessions
       Session EC-TuP

Paper EC-TuP5
Characteristics of the Polymer formed on via Sidewall during RIE Process and its Removal

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Poster Session
Presenter: J. Song, Samsung Electronics Co., Ltd., Korea
Authors: J. Song, Samsung Electronics Co., Ltd., Korea
J. Kim, Samsung Electronics Co., Ltd., Korea
H. Seo, Hanyang University, Korea
Y. Kim, Hanyang University, Korea
H. Jeon, Hanyang University, Korea
Correspondent: Click to Email
Via contact holes, act as electrical connection between the upper and lower metal layers through inter-metal dielectric, are generally patterned by photo lithography and reactive ion etching (RIE) processes, and the patterned photoresist after the formation of via holes is conventionally removed by the combination of remote plasma ashing and wet organic stripping. It is very critical to remove completely polymer formed on via sidewall and bottom during RIE process to have reliable metal filling and good contact resistance. Via holes were formed by using RIE process with CHF@sub 3@/CF@sub 4@ gas under the same processing conditions for the state-of-the art DRAM process. The surface morphology of polymer before and after cleaning process was observed by using in-line scanning electron microscopy (SEM), vertical SEM and transmission electron microscopy (TEM). The chemical compositions and structures of polymer were analyzed by using energy dispersive spectroscopy (EDS) and Auger electron spectroscopy (AES). TEM and EDS study revealed that the side wall polymer were grown from the cap TiN layer on Al and showed the truncated cone shape with the thickness in the range of 200~400Å. This indicates that via polymer layer becomes a very critical issue when the etch stop layer is TiN. Bottom polymer layer showed double layer structure with two distinct chemical compositions. The lower layer with the thickness of about 50Å showed a similar chemical characteristic to the side wall polymer while the upper polymer layer with the thickness of about 200Å showed no fluorine content. In this study, we will investigate the removal characteristics of polymer during RIE process at various ashing and stripping conditions. Preliminary results indicated that the low temperature remote oxygen plasma ashing and hydroxylammoniumsulfate based wet stripping were very effective to remove polymer formed on the side and bottom of via holes during RIE process.